First Human Cases of Two Retroviruses Discovered Among People in Contact With Monkey Meat in Cameroon

Scientists have detected the first human cases of two retroviruses among two people in rural Cameroon who hunt monkeys and other primates, according to a study presented on Friday at the 12th Conference on Retroviruses and Opportunistic Infections in Boston, the New York Times reports (Altman, New York Times, 2/26). Scientists from CDC and Johns Hopkins University discovered the first human cases of the retroviruses -- called Human T-Lymphotomic Virus types 3 and 4 -- while studying 930 residents of Cameroon who were "in frequent contact with monkey meat," AFP/Australian reports. To date, there has been no evidence of transmission of HTLV-3 or HTLV-4 from human to human and the viruses have not been linked to any disease. Research has begun in Cameroon to evaluate the health of people living with the virus and to contact their sexual partners, according to Dr. Walid Heneine, a CDC virologist who led the study. According to CDC, about 22 million people worldwide have HTLV-1, which has been known to cause leukemia and inflammation, or HTLV-2, which has been linked to neurological problems. About 5% of people with HTLV-1 or HTLV-2 develop a related illness (AFP/Australian, 2/27). Although HTLV-3 and HTLV-4 have not been associated yet with disease among people, HTLV viruses -- like HIV -- can have incubation periods that can last decades, Reuters reports (Fox, Reuters, 2/25). The study findings indicate that "the sort of cross-species infection that first put the AIDS virus into human beings continues today and probably is not rare," according to the Washington Post (Brown, Washington Post, 2/26).

More Study Findings, Comment
Through antibody screening and genetic analysis, researchers also found at least six different simian retroviruses that had jumped from primates to infect 13 humans, including one hunter infected with HTLV-3, which is "genetically similar" to Simian T-Lymphotomic Virus type 3, and one hunter infected with HTLV-4, a virus "distinct" from all previously known human or simian T-lymphotomic viruses. The other 11 people were infected with HTLV-1 or STLV-1 (CDC release, 2/25). "The appearance of these retroviruses in humans demonstrates that cross-species transmissions may be frequent," Heneine said. The researchers plan to conduct additional tests on a group of 4,000 people in rural areas of Cameroon to determine the extent of retroviral transmission among humans, according to AFP/Australian (AFP/Australian, 2/27). "It's a new virus. You pause, you say, 'Where is the virus coming from?'" Heneine said, adding, "I don't think you should be taking it lightly" (Reuters, 2/25).

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